Structural insights on anti-biofilm mechanism of heated slightly acidic electrolyzed water technology against multi-resistant Staphylococcus aureus biofilm on food contact surface

Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens and detachment of multi-resistant Staphylococcus aureus(MRSA)biofilm.Furthermore.the underlying mechanism of MRS A biofilm under heated SAEW at 40℃treatment on metabolic profiles was investigated.The results showed that the heated SAEW at 40℃significantly effectively against foodbome pathogens of 1.96-7.56(lg(CFU/g))reduction in pork,chicken,spinach,and lettuce.The heated SAEW at 40℃treatment significantly reduced MRS A biofilm cells by 2.41(lg(CFU/cm^(2))).The synergistic effect of SAEW treatment showed intense anti-biofilm activity in decreasing cell density and impairing biofilm cell membranes.Global metabolic response of MRSA biofilms,treated by SAEW at 40℃,revealed the alterations of intracellular metabolites,including amino acids,organic acid,fatty acid,and lipid.Moreover,signaling pathways involved in amino acid metabolism,energy metabolism,nucleotide synthesis,carbohydrate metabolites,and lipid biosynthesis were functionally disrupted by the SAEW at 40℃treatment.As per our knowledge,this is the first research to uncover the potential mechanism of heated SAEW treatment against MRSA biofilm on food contact surface.

Staphylococcus aureus and biofilms:transmission, threats, and promising strategies in animal husbandry

Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and exacerbates S. aureus infection by allowing the bacteria to adhere to pathological areas and livestock product surfaces, thus triggering animal health crises and safety issues with livestock products. To solve this problem, in this review, we provide a brief overview of the harm caused by S. aureus and its biofilms on livestock and animal byproducts(meat and dairy products). We also describe the ways in which S. aureus spreads in animals and the threats it poses to the livestock industry. The processes and molecular mechanisms involved in biofilm formation are then explained. Finally, we discuss strategies for the removal and eradication of S. aureus and biofilms in animal husbandry, including the use of antimicrobial peptides, plant extracts, nanoparticles, phages, and antibodies. These strategies to reduce the spread of S. aureus in animal husbandry help maintain livestock health and improve productivity to ensure the ecologically sustainable development of animal husbandry and the safety of livestock products.

Molecular Detection of Biofilm-Producing <i>Staphylococcus aureus</i>Isolates from National Orthopaedic Hospital Dala, Kano State, Nigeria

This study evaluated biofilm formation and antibiotic susceptibility in 36 clinical S. aureus isolates recovered from orthopaedic patients and detected the presence of intercellular adhesion and adhesin genes. Staphylococcus aureus was isolated from nasal swab, wound and urine specimens collected from orthopaedic patients in National Orthopaedic Hospital Dala, Kano over a period of three months. The isolates were identified using rapid identification kit for Staphylococcus species. The antibiotics susceptibility of the isolates was determined using modified disc diffusion method. Phenotypically, the biofilm formation was assessed using the Congo red agar method and microtitre plate assay. Polymerase chain reaction (PCR) analysis was used to detect biofilm-associated genes and characterize the isolates. The isolation rate of S. aureus from the samples (n = 134) was 26.8%, mainly from nasal swab (36%) and wound swab (36%). A total of 19 (52.7%) of the isolates showed positive for slime production. Majority of the isolates 29/36 (81.6%) were biofilm positive with only 2 (5.5%) and 5 (13.8%) as strong biofilm-formers and moderate biofilm-formers respectively. Molecular evaluation of the biofilm-associated genes in 12 S. aureus isolates revealed the prevalence of bbp genes (25%), clfA genes (16.6%) and the icaA (8.3%). None of the isolates harboured the fnbA and cna genes. There is no significant difference (P > 0.05) in the antibiotic resistance pattern between biofilm-positive and biofilm-negative S. aureus isolates. This result revealed that phenotypically most of the S. aureus isolates were biofilm formers but few of them chromosomally harbour the biofilm-associated genes.

Mutations of the brpR and brpS genes affect biofilm formation in Staphylococcus aureus

BACKGROUND In the United States,Staphylococcus aureus(S.aureus)kills tens of thousands of individuals each year and the formation of a biofilm contributes to lethality.Biofilm-associated infections are hard to treat once the biofilm has formed.A new stilbene drug,labeled SK-03-92,was shown to kill S.aureus and affected transcription of two genes tied to a putative two-component system(TCS)we have named brpR(biofilm regulating protein regulator)and brpS(biofilm regulating protein sensor).AIM To determine if BrpR and BrpS regulate biofilm formation,brpR and brpS mutants were assessed using biofilm assays compared to wild-type S.aureus.METHODS A combination of biofilm and quantitative real-time-polymerase chain reaction assays were used.In addition,bioinformatic software tools were also utilized.RESULTS Significantly more biofilm was created in the brpR and brpS mutants vs wild-type cells.Quantitative real-time polymerase chain reactions showed the brpS mutant had differences in transcription of biofilm associated genes that were eight-fold higher for srtA,two-fold lower for lrgA,and 1.6-fold higher for cidA compared to wild-type.Bioinformatic analysis demonstrated that the S.aureus brpR/brpS TCS had homology to streptococcal late-stage competence proteins involved in celldeath,increased biofilm production,and the development of persister cells.CONCLUSION Our study suggests that brpR/brpS is a TCS that may repress S.aureus biofilm production and be linked to late-stage competence in S.aureus.

Penicillin-resistant characterization of Staphylococcus aureus isolated from bovine mastitis in Gansu,China

Bovine mastitis caused by Staphylococcus aureus is difficult to treat because of increasing resistance against antibiotics, especially penicillin. β-Lactamase and biofilm are responsible for penicillin resistance of S. aureus. The aim of this study was to investigate the β-lactamase activity and biofilm formation capacity of 37 penicillin-resistant S. aureus strains （35 were blaZ positive and 2 were blaZ negative） from bovine mastitis in Gansu Province, China, as well as to measure the intercellular adhesion genes icaA and icaD of these strains. β-Lactamase Test Kit was used to determine the β-lactamase activity, biofilm formation was tested by semi-quantitative adherence assay method. Moreover, the presence of icaA and icaD were measured by PCR. A total of 32 penicillin-resistant S. aureus strains, including the two blaZ-negative strains, were identified as β-lactamase producers. All tested S. aureus isolates produced biofilm in the microtiter plate assay. Meanwhile, all these strains were PCR-positive for the ica locus, icaA and icaD. The study indicated high prevalence of β-lactamase activity, biofilm-forming capacity, and the ica genes among the penicillin-resistant S. aureus isolates, and implied that S. aureus resistant to penicillin was attributed to multiple mechanisms.

The staphylococcal nuclease prevents biofilm formation in Staphylococcus aureus and other biofilm-forming bacteria

The staphylococcal nuclease, encoded by the nucl gene, is an important virulence factor of Staphylococcus aureus. However, the physiological role of the nuclease has not been fully characterized. The current study observed that biofilm development could be prevented in staphylococcal nuclease-producing strains of S. aureus; however, when the nucl gene was knocked out, the ability to form a biofilm significantly increased. Scanning electron and confocal scanning laser microscopy were used to evaluate the role of the nucl gene in biofilm formation. Moreover, the nucl gene product, staphylococcal nuclease, and re- combinant NUC1 protein were found to have a visible effect on other biofilm-forming bacteria, such as Pseudomonas aeru- ginosa, Actinobacillus pleuropneurnoniae, and Haernophilus parasuis. The current study showed a direct relationship between staphylococcal nuclease production and the prevention of biofilm development. The findings from this study underscore the important role of staphylococcal nuclease activity to prevent biofilm formation in S. aureus. They also provided evidence for the biological role of staphylococcal nucleases in other organisms.

Effect of New Dayuan powder on methicillin-resistant Staphylococcus aureus biofilms in vitro

OBJECTIVE:To observe the effects of New Dayuan powder(NDYP)on Methicillin-resistant Staphylococcus aureus(MRSA)biofilms and the embedded bacteria in vitro.METHODS:2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2 H-tetrazolium-5-carboxanilide(XTT)assays were used to study the effects of NDYP on developing MRSA biofilms:100μL of bacterial culture and100μL drug solution were added to wells of96-well plates.After 24 h of incubation,the plates were washed and XTT-phenazine methyl sulfate(PMS)was added to enable counting of the number of live bacteria in biofilms using a microplate reader.XTT assays were also used to explore the effects of NDYP on mature MRSA biofilms:100μL of bacterial culture were added to wells of 96-well plates.Bacteria were cultured in the plates for 24 h,and then drug solution was added.The plates were cultured for another 24 h,and then XTT-PMS was added to detect the number of live bacteria in the biofilms.Scanning electron microscopy(SEM)was used to observe the effects of NDYP on mature MRSA biofilms:washed and sterilized glass coverslips were added to 24-well plates.Bacterial culture was added.After 24 h of incubation,drug solution was added.After another 24 h of incubation,the samples were observed by SEM.RESULTS:XTT assays showed that the number of live bacteria in both developing and mature MRSA biofilms decreased significantly(P<0.01)after the administration of NDYP.SEM images showed that NDYP could destroy the structure of the bacteria and resulted in uneven thickness of MRSA biofilms.CONCLUSION:In vitro,NDYP has obvious inhibitory effects on the formation of MRSA biofilms and on mature biofilms.

Semi-Automated Method for Multi-Tasking Measurement of Microbial Growth, Capsule, and Biofilm Formation

The majority of bacterial infections involve the formation of biofilms. Biofilm formation is nutrient and growth dependent. Determination of the effects of nutrients on exopolysaccharide production and bacterial growth is labor and time intensive. We tested whether the Bioscreen C (Growth Curves, Inc.) would have utility as a high-throughput tool in the measurement of fundamental phenotype expression, as it relates to growth conditions. Within 48 - 72 hr, reproduceble, statistically significant data on the affects of growth conditions on generation time, capsule production and biofilm formation (maximally for 25 different conditions per 24 hr run cycle;n = 4) were obtained. Although all S. aureus strains produced similar amounts of capsule, sarA– and agr– strains grew significantly slower than parent strain (1.6 fold slower) and produced significantly (p 0.05) less biofilm (~2 fold). E. coli growth rate, biofilm and capsule production in simulated nephropathic urine medium was similar for urine with insulin (20 μU). Addition of insulin to urine medium with proline increased generation time, capsule and biofilm production. Findings from this study show that the Bioscreen C is a rapid, reproducible, and easily manipulated system to concurrently measure bacterial growth, biofilm formation, and capsule production. In addition, there is the potential for further applications of this system by expanding the types of detector dyes used.

Antibiofilm activity of a-mangostin extracted from Garcinia mangostana L. against Staphylococcus aureus

Objective: To isolate a-mangostin(AMG) from the peels of mangosteen(Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus(S. aureus) strains, one of which was methicillin-resistant S. aureus(MRSA) and the other two strains were methicillinsensitive S. aureus(MSSA).Methods: AMG in n-hexane fraction was isolated on a silica gel column and chemically analyzed by HPLC and NMR. The antibiofilm activity of this compound was investigated by using a 96-well plate model for the formation of biofilms. Biofilm biomass was quantified using crystal violet. The viability of cells was observed under confocal microscopy using LIVE/DEAD Bac Light stains. Biofilm composition was determined using specific chemical and enzyme tests for polysaccharide, protein and DNA. Membranedamaging activity was assayed by measuring the hemolysis of human red blood cells in presence of AMG.Results: The results indicated that the isolated AMG, with a purity that exceeded 98%,had minimal inhibitory concentrations in the range of 4.6–9.2 mmol/L for the three strains tested. Interestingly, the MSSA strains were more sensitive to AMG than the MRSA strain. Minimal bactericidal concentrations were 2-fold higher than the minimal inhibitory concentration values for the three strains, indicating that AMG was a bactericidal compound. AMG also prevented biofilm formation effectively, albeit that again the MRSA strain was the most resistant. Interestingly, biofilms of the MRSA strain contained protein as a main component of the extracellular matrix, whereas this was polysaccharide in the MSSA strains. This might relate to the resistance of the MRSA 252 strain to AMG.Assays using human red blood cells indicated that AMG caused significant membrane damage with 50% of cell lysis occurred at concentration of about 36 mmol/L.Conclusions: Our results provide evidence that the isolated AMG has inhibitory activity against biofilm formation by S. aureus, including MRSA. Thus, isolated AMG proposes a high potential to develop a novel phytopharmaceutical for the treatment of MRSA.

Determination of the Anti-Adhesive and Anti-Biofilm Capacity of a Wheat Extract on <i>Staphylococcus aureus</i>in Farms

The formation of biofilm by pathogenic microorganisms has become a problem in the livestock industry since it is considered a potential source of infection for farm animals while increasing microbial resistance to physical and chemical agents. Some plant extracts, such as soluble wheat extract, have been shown to be effective in inhibiting or destroying the biofilm of certain micro-organisms under specific conditions. The objective of this study is to evaluate the capacity of the pathogen to form biofilm on different surfaces used in livestock, as well as to evaluate the anti-biofilm capacity of the soluble wheat extract against S. aureus on these surfaces. The inhibition potential of inhibition or destruction of biofilm was tested in vitro. Wheat extract at a concentration of 0.29 mg/100mL showed anti-biofilm activity on S. aureus, inhibiting its formation, as well as destroying it greatly after a contact time of 24 hours, on those surfaces where the microorganism presents more adhesion capacity.

Kinetics of <i>Candida albicans</i>and <i>Staphylococcus aureus</i>Biofilm Initiation on Herpes Simplex Virus (HSV-1 and HSV-2) Infected Cells

This study examines the kinetics of S. aureus and C. albicans adherence as it relates to HSV replication and corresponding dynamic display of shared receptors. HeLa cells infected for various times with HSV-1 gL86 or HSV-2 333gJ-(MOI 50) were incubated with S. aureus ATCC 25923 or C. albicans yeast and CFU measured. Over time, S. aureus adherence to HSV-1 infected cells was relatively stable for 45 min then decreased to 0.8 of virus-free control, before cycling at 15-to-30 min intervals. In contrast, staphylococcal adherence to HSV-2 infected cells proceeded at a more gradual rate, increasing to control levels at ~105 min before decreasing to a nadir at 165 min. Yeast adherence to HSV-1 infected cells remained relatively unchanged for the first 75 min then increased 2-fold before returning to its original level. This pattern is repeated over the next 90 min. While a similar pattern with C. albicans and HSV-2 was measured, it occurred more rapidly. Our model shows that while the interaction of both HSV-1 and HSV-2 with S. aureus is both dynamic and inhibitory, C. albicans interaction with HSV-2 is more permissive than HSV-1. However, the interaction of both microbes with HSV-infected cells in this model system appears to be independent of α5B1, CD36 and HSP60 viral-regulated receptor expression. These findings indicate that microbiome interactions across taxonomic kingdoms are more complex than previously thought.

Enhancing near-infrared II photodynamic therapy with nitric oxide for eradicating multidrug-resistant biofilms in deep tissues

Nitric oxide(NO)enhanced photodynamic therapy(PDT)is a promising approach to overcome drug tolerance and resistance to biofilm but is limited by its short excitation wavelengths and low yield of reactive oxygen species(ROS).Herein,we develop a compelling degradable polymer-based near-infrared II(NIR-II,1000-1700 nm)photosensitizer(PNIR-II),which can maintain 50%PDT efficacy even under a 2.6 cm tissue barrier.Remarkably,PNIR-II is synthesized by alternately connecting the electron donor thiophene to the electron acceptors diketopyrrolopyrrole(DPP)and boron dipyrromethene(BODIPY),where the intramolecular charge transfer properties can be tuned to increase the intersystem crossover rate and decrease the internal conversion rate,thereby stabilizing the NIR-II photodynamic rather than photothermal effect.For exerting a combination therapy to eradicate multidrug-resistant biofilms,PNIR-II is further assembled into nanoparticles(NPs)with a synthetic glutathione-triggered NO donor polymer.Under 1064 nm laser radiation,NPs precisely release ROS and NO that triggered by over-expressed GSH in the biofilm microenvironment,thereby forming more bactericidal reactive nitrogen species(RNS)in vitro and in vivo in the mice model that orderly destroy biofilm of multidrug-resistant Staphylococcus aureus cultures from clinical patients.It thus provides a new outlook for destroy the biofilm of deep tissues.

Hemolysins of <i>Staphylococcus aureus</i>—An Update on Their Biology, Role in Pathogenesis and as Targets for Anti-Virulence Therapy

Staphylococcus aureus is a dangerous gram positive bacterial pathogen which, not only evades the host’s immune system but also can destroy the leucocytes especially neutrophils. It has an embodiment of virulence factors most of which are secreted. Staphylococcus aureus secretes a number of toxins which cause tissue damage and facilitate spreading and nutrients uptake. Among the toxins, hemolysins α, β, γ, δ and Panton Valentine Leukocidin (PVL) are unique that they drill pores in the membrane, leading to the efflux of vital molecules and metabolites. Hemolysins also help in the scavenging of iron, although many of them also have leucolytic properties. α-hemolysin, also known as α-toxin, is the most prominent cytotoxin which damages a wide range of host cells including epithelial cells, endothelial cells, erythrocytes, monocytes, keratinocytes and it damages cell membrane and induces apoptosis. β-Hemolysin significantly affects human immune cell function. It has Mg2+ dependent sphingomyelinase activity and degrades sphingomyelin of plasma membrane into phosphorylcholine and ceramides. The bi-component leukocidins, which include γ-hemolysin and PVL, attack human phagocytic cells and greatly contribute to immune evasion. Delta toxin is a low molecular weight exotoxin with a broad cytolytic activity. Virulence determinants, quorum sensing and biofilm synthesis provide some attractive targets for design and development of a new group of antimicrobial compounds. This review provides an update on the structure, biological functions of hemolysins and their role in quorum sensing/biofilm synthesis (if any) and as effective therapeutic targets for anti-virulence drug development. We have tried to bring together information available on various aspects of hemolysins and highlighted their distribution among all species of Staphylococcus and other bacteria. We have updated the status of development of candidate drugs targeting the hemolysins for anti-virulence therapy as it offers an additional strategy to reduce the severity of infection and which would, through quorum quenching, delay the development biofilms leading to drug resistance.

水飞蓟素对S.aureus ATCC25923生物膜及其毒力因子的影响

目的:探究水飞蓟素对S.aureus ATCC25923生物膜及其毒力因子的影响。方法:采用结晶紫染色法检测水飞蓟素对S.aureus ATCC25923生物膜形成的抑制及清除作用,MTT染色法探究水飞蓟素对其生物膜代谢的影响,冻干血浆和无菌脱纤维羊血探究水飞蓟素对其凝固酶表达和溶血活性的影响,同时用光学显微镜观察不同浓度水飞蓟素对其生物膜影响及傅里叶红外分析细菌成分变化。结果:水飞蓟素对S.aureus ATCC25923的最小抑菌质量浓度(MIC)为0.5 mg/mL,MIC浓度下的水飞蓟素对S.aureus ATCC25923生物膜的抑制率达到90%,清除率达到89.2%,且低剂量的水飞蓟素能够显著抑制其溶血活性和凝固酶的表达。结论:水飞蓟素对金黄色葡萄球菌的生物膜形成具有很好的抑制以及清除作用,同时能够显著抑制其毒力因子的表达。

The Ciliate Protist <i>Tetrahymena pyriformis</i>as a Cellular Adhesion Model for the Pathogenic Bacterium <i>Staphylococcus aureus</i>

Staphylococcus aureus is one of the main pathogenic agents responsible for nosocomial and community-acquired bacterial infections. The pathogenicity of this Gram-positive bacterium is ensured by its different adhesion factors. Collagen and the extracellular glycoprotein adhesin are among the Staphylococcus most important virulence factors. It has been shown that most of the S. aureus strains carry the ica operon, responsible for biofilm production. However, the coexpression of the icaA and the icaD genes is necessary for complete biofilm synthesis. The aim of our study was to study a collection of 15 clinical strains of S. aureus from different sources for the presence of can and icaD genes coding intercellular adhesion proteins. We also intended to estimate the strains’ ability to form biofilms by the red Cong method and to test the adhesion ability of S. aureus to the ciliated protist Tetrahymena pyriformis, which we used as a novel cellular adhesion model. Finally, we checked the adhesion’s inhibition capacity of some plants extracts. The molecular detection of adhesion genes revealed that 80% of strains are cna positive, and 73% are icaD positive. Qualitative biofilm production of S. aureus revealed that 66.6% of strains were slime producers. The adhesion test revealed that 20% of strains are strongly adhering to T. pyriformis and that the Clematis cirrhosa extract has an anti-adhering effect of S. aureus to the ciliate T. pyriformis.

Research Progress of Quorum Sensing in Staphylococcus aureus

Quorum sensing refers to the phenomenon that bacteria sense signal molecules in the environment and regulate a series of genes.At present,the known quorum sensing systems in Staphylococcus aureus are the Agr system and the LuxS/AI-2 system.They will be activated when the bacterial concentration is equal to or greater than 107/ml,and by regulating the corresponding genes,bacteria can indirectly or directly regulate the production and degradation of biofilms,the secretion of bacterial toxins and the growth of bacteria.In this paper,we summarized the research progress of quorum sensing in S.aureus by consulting relevant literatures at home and abroad on quorum sensing in S.aureus,so as to find a new direction for the future research on S.aureus.

Inhibitory Activity of Ethanol Extract from <i>Artemisia argyi</i>on a Clinical Isolate of <i>Staphylococcus aureus</i>

As a traditional herbal medicine for the treatment of many disorders, Artemisia argyi has shown many valuable bioactivities, but little is known about its effect on Staphylococcus aureus. In this study, the growth, the biofilm formation and the pathogenicity of S. aureus cultivated with or without ethanol extract of A. argyi were tested using microtitre plate assay, Confocal Laser Scanning Microscope (CLSM) system and mice infection assay. Results showed that the growth and the biofilm formation of S. aureus in the test group with ethanol extract of A. argyi were significantly lower than those of the control group without ethanol extract of A. argyi. With CLSM system we could observe that the biofilm structure of the test group had looser and less biomass compared with the control group. After infection of S. aureus, the survival of mice in test group that were given 0.2 mL 100 mg/mL ethanol extracts of A. argyi was higher than the control group. Histopathological analyses showed that the tissue damage of mice in test group was less than that in control group. These results suggested that ethanol extract of A. argyi had inhibitory effect on S. aureus and could protect mice from death induced by S. aureus infection.

鱼腥草素钠联合EDTA-Na_2对生物被膜菌的影响

目的探索鱼腥草素钠(SH)联合乙二胺四乙酸二钠(EDTA-Na2)对生物被膜菌的影响,寻找潜在的抗生素替代品。方法通过微量稀释法以及棋盘法,测定SH和EDTA-Na2对铜绿假单胞菌(Pseudomonas aeruginosa,PA)、金黄色葡萄球菌(Staphylococcus aureus,SA)、白色念珠菌(Candida albicans,CA)的最小抑菌浓度(MIC)和最小膜清除浓度(MBEC)以及两药协同点;通过平板稀释涂布法测定3种菌在协同点的生存曲线;扫描电子显微镜法(SEM)观察PA、SA和CA生物被膜的形态。结果 SH对PA、SA和CA的MIC分别为2.048、0.064、0.064 mg/m L,MBEC分别为2.048、0.256、0.512mg/m L;EDTA-Na2对PA、SA和CA的MIC分别为3.75、0.938、0.117 mg/m L,MBEC分别为15、3.75、30 mg/m L;SH联合EDTA-Na2(SH/EDTA-Na2)对PA、SA和CA的MIC(mg/m L)分别为0.256/0.938、0.008/0.233、0.008/0.029,MBEC(mg/m L)分别为0.512/3.722、0.032/0.469、0.064/0.938;SEM观察到两药联合对细菌的生长抑制和生物被膜的清除有明显作用,载体上的细菌显著减少,未见或仅有少量的生物被膜结构,与空白对照组比较差异明显。结论 SH与EDTA-Na2具有协同作用,二者联合能够显著增强SH对PA、SA和CA的生长抑制和生物被膜的清除作用。

食源性金黄色葡萄球菌生物膜形成调控与生物防控策略研究进展

生物膜是很多食源性致病菌应对各种极端环境、杀菌理化因子以及维持菌体内环境稳定的重要基质屏障。数据显示,有超过80%的细菌感染由生物膜引起,尤以金黄色葡萄球菌感染多见。食源性金黄色葡萄球菌是引发细菌性食物中毒和食品安全事故的重要风险源,特别是多重耐药菌株。金黄色葡萄球菌的耐药性、致病性和免疫逃逸与生物膜复杂的三维结构有重大关系。由于生物膜结构基因和调控因子结构相对保守,现已成为金黄色葡萄球菌生物防控新的重要的效应靶点。本文从多糖细胞间黏附素、胞外DNA和生物膜形成相关蛋白等角度阐明了生物膜形成机制,从群体感应系统(如Agr系统和LuxS/AI-2群体感应系统)、全局性调控因子(如附属调节因子Sar和转录因子SigB)及双组分信号转导系统(如SrrAB系统、SaeRS系统、ArlRS系统、LytRS系统和WalKR系统)等角度系统阐述了生物膜形成调控机制。最后,从抗菌肽(蛋白)、植物源化合物、生物酶、抗菌药物等角度提出新的防控策略,以期为食源性金黄色葡萄球菌的生物防控提供指导。

百里香酚对犊牛源生物被膜阳性金黄色葡萄球菌耐药性的消除作用

为了了解内蒙古地区犊牛病料中生物被膜阳性金黄色葡萄球菌的流行情况、耐药情况及百里香酚对生物被膜阳性金黄色葡萄球菌耐药性的消除作用。本试验采用生化鉴定和PCR方法,对采集到的104份犊牛病料进行金黄色葡萄球菌的分离鉴定;采用K-B法检测了金黄色葡萄球菌分离株对18种抗菌药物的敏感性;采用改良结晶紫染色法测定分离株的生物被膜形成能力;选取2株生物被膜强阳性菌株,采用微量肉汤稀释法测定百里香酚对分离株的最小抑菌浓度,并进行百里香酚耐药性消除试验。结果显示,在104份犊牛病料中共分离鉴定获得43株金黄色葡萄球菌。药敏试验结果显示,金黄色葡萄球菌分离株对氨苄西林、头孢西丁、卡那霉素、复方新诺明和红霉素5种抗菌药物的耐药率达到50.0%以上;74.4%(32/43)的分离株为多重耐药株。生物被膜形成能力强、中、弱和无生物被膜形成能力的分离株分别占比23.3%(10/43)、16.3%(7/43)、32.6%(14/43)和27.9%(12/43);生物被膜阳性株中83.9%(26/31)为多重耐药株。百里香酚对2株生物被膜强阳性株的最小抑菌浓度均为256 mg/mL,经百里香酚处理后均恢复了对头孢噻肟的敏感性。结果表明,百里香酚对生物被膜阳性金黄色葡萄球菌具有一定的耐药消除作用。